subject code :(17558) 1 23...by adjustable side arms. gloves for hand and arm protection: to...
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MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION (Autonomous)
(ISO/IEC - 27001 - 2005 Certified)
SUMMER-16 EXAMINATION Model Answer
_____________________________________________________________________________________________________
Subject code :(17558) Page 1 of 23
Important Instructions to examiners:
1) The answers should be examined by key words and not as word-to-word as given in the model answer scheme. 2) The model answer and the answer written by candidate may vary but the examiner may try to assess the understanding level of the candidate. 3) The language errors such as grammatical, spelling errors should not be given more Importance (Not applicable for subject English and Communication Skills. 4) While assessing figures, examiner may give credit for principal components indicated in the
figure. The figures drawn by candidate and model answer may vary. The examiner may give credit for any equivalent figure drawn.
5) Credits may be given step wise for numerical problems. In some cases, the assumed constant values may vary and there may be some difference in the candidate’s answers and model answer. 6) In case of some questions credit may be given by judgement on part of examiner of relevant answer based on candidate’s understanding. 7) For programming language papers, credit may be given to any other program based on
equivalent concept.
MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION (Autonomous)
(ISO/IEC - 27001 - 2005 Certified)
SUMMER-16 EXAMINATION Model Answer
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Q No. Answer marks Total marks
1-A Any 3 12
1A-a Hazard: A hazard in anything in the work place that has the potential to harm
people. It cal include objects in the workplace such as machinery or dangerous
chemicals.
Types of hazards :
1) Mechanical hazards
2) Electrical hazards
3) Noise hazards
4) Radiation hazards
5) Explosion hazards
6) Toxic hazards
7) Chemical hazards
1
3
4
1A-b Sources and protection of noise hazard:
i) Reduction at source: wherever possible it would be advisable to reduce the
noise at the source itself.eg change the bearings if it makes noise due to wear.
ii) Vibration isolation: In case of machine like reciprocating compressors and
power presses, the mechanical vibrations are transmitted through the structures,
walls and the floor which increases the noise level at the workplace. Reduction
of noise levels can be achieved by,
a) Using vibration resilient mounts to fix the machine to foundations.
b) Special heavy foundations with a large weight compared to the weight of
machine.
iii) Vibration Damping:Machine parts, ventilation duct cause noise in this
1 mark
each for
any 4
4
MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION (Autonomous)
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SUMMER-16 EXAMINATION Model Answer
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manner. Thenoise in these cases can be reduced by damping- by stiffening the
member.
iv) Silencers: Where noise due to movement of gases or air is the problem,
silencers are the right solution. Silencers can be used at the inlet/outlet of
compressors, exhausts, release of steam and gases and pressure relief valves of
pneumatic machines.
v) Noise insulation:It may be necessary to insulate the source from all the sides
although insulating two or three sides also give reduction of a lower degree.
vi) Noise absorption: Noise absorption material, normally soft and porous,
prevent reflection of noise and also convert some of the noise energy into heat
energy.
1A-c Different respiratory equipments used as personal protective equipments
in a chemical plant are:
1. Air Purifying Type
a. Mechanical filter respirators:
b. Canister gas masks:
c. Chemical Cartridge Respirators:
2. Air Supplied Type:
This includes-
a. Air line respirators:
b. Fresh air or Suction Hose Masks:
3. Self Contained Breathing Apparatus:
These are mainly of three types.
a. With compressed air or oxygen cylinder
b. Oxygen rebreathing or recirculating type
c. Oxygen regenerating type
4 4
1A-d Comparison on respiratory and non respiratory protective equipment: 4
MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION (Autonomous)
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SUMMER-16 EXAMINATION Model Answer
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1. Respiratory protective equipment should only be used as a final resort to
achieve health and safety, whereas non respiratory protective
equipment are to be used compulsorily when working in a plant.
2. Respiratory protective equipment should be selected as the per the
nature of environment whereas non respiratory protective equipment
are same in all environment.
2
2
1-B Any 1 6
1B-a Sources of Radiation Hazard :
Nuclear Industry, Hospital (X-ray division)are some industries where radiation
hazard takes place.
The radiation is produced when atoms of natural radio active material decay or
split, generating streams of photons vibrating at enormous speeds in wavelike
form. Radiation has two basic forms: ionizing and nonionizing. In chemical
plants workers may be exposed to various forms of nonionizing radiation.
Radiation hazards occurred during testing of nuclear weapons, establishment of
nuclear power plants, mining and refining of plutonium and thorium and
preparation of radioactive isotope.
6 6
1B-b Various protections used against Eye:
Protecting eyes and faces from physical, chemical and radiation hazard are of
prime importance. These protective devices are available in various types and
styles. Selection should be made depending upon the nature of hazards
involved.
Welding shield are made of non-flammable material, are opaque to dangerous
radiation and are poor conductors of heat. Face shields protect face and neck
from flying particles, chemical splashes etc. Tinted transparent plastic shields
protect against glare. The head band of the face shield should be such that the
face piece can be pushed upwards when so required.
3
6
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In face and eye protection equipment, laminated lens should never be used. The
most important thing in eye protection device is that the lens, whether glass or
permanent plastic, should be optically correct and completely free from flaws
and distortions. These should be comfortable for wear. These should be cleaned
and kept in a good state of repair regularly and all workers should be trained for
proper use of such devices.
Various protections used against Head:
There are four widely used types of head protection.
1. Industrial safety helmet s which can protect against falling objects or
impact with fixed objects.
2. Caps, helmets etc. which can protect the scalp and hair from
entanglement or can protect the head from contamination with toxic or
nuisance dust, or protect from dirt carried within the hair.
3. Industrial scalp protectors such as Bump Caps can protect process
workers from striking their heads against fixed objects when working in
confined spaces.
4. Crash helmets, cycling helmets and climbing helmets which are
intended to protect wearers should they be involved in a fall.
3
2 Any 4 16
2-a Precautions taken against electrical hazards:
The danger of injury through electrical shock is present whenever electrical
power is used.
1. All electrical should be adequately insulated, grounded or isolated to
prevent bodily contact with any source of dangerous potentials.
2. To prevent electrical shock, ensure that all equipment are properly
grounded.
3. To reduce the risk of shock, do not contact any electrical components,
1 mark
each for
any 4
4
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SUMMER-16 EXAMINATION Model Answer
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and keep the work area dry.
4. Check all equipment regularly and wear the proper protective equipment
when working with high voltages or currents.
5. The primary effects of electrical shock are due to current actually
flowing through the body. Electrical burns occur when the body
completes a circuit connecting the power source with the ground.
Although the resistance of dry , unbroken skin to electrical current is
relatively high, the amount of current necessary to kill a person is small.
Therefore it is easy to exceed lethal levels of current flow, especially if
the skin is broken, wet or damp with sweat.
2-b Personal protective equipment: (any four)
Ear Plug :
It is personnel protective device for ear which is put inside the ear. They are
worn in the ear canal, sealing the entrance to the ear
Ear Muffs :
It is again a personnel protective device for ear which is placed on the ear
thereby covering the ear completely.This can be worn over the head, behind the
neck or under the chin. The cups may also be attached to some safety helmets
by adjustable side arms.
Gloves for hand and arm protection:
To safeguard workers there will be purpose-made gloves, supplied by
manufacturers specializing in products , capable of protecting them from the
hazards.
Helmets, hard cap for head protection :
Industrial safety helmet can protect the worker against following objects or
impact with fixed objects. Caps and helmets protect the head of contamination
with toxic substance.
1 mark
each
4
MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION (Autonomous)
(ISO/IEC - 27001 - 2005 Certified)
SUMMER-16 EXAMINATION Model Answer
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Safety boot or shoes for foot protection :
The safety boot or shoe is the most common type of safety footwear, and would
normally have a steel toe cap. It helps to protect the feet from corrosive or toxic
materials.
Goggles for eyes protection:
Goggles projects the eyes from dust , gases, welding arc , lesser light, toxic or
chemical substances.
Apron/ lab coat for body protection
2-c Dry chemical extinguisher:
Working :On fires involving either liquids in containers or spilled liquids,
direct the jet towards the near edge of the fire and with rapid sweeping motion,
drive the fire towards the far edge until all the flames are extinguished. On fires
in falling liquids, direct the jet at the base of the flame and sweep upwards. On
2
2
4
MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION (Autonomous)
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SUMMER-16 EXAMINATION Model Answer
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fires in electrical equipments, direct the jet straight at the fire. Where the
equipment is closed, direct the jet into any opening with the object of
penetrating the interior.
2-d
Objectives of Safety Audit are :
1. Confirm that safety, health, fire and environmental program activities
and controls are in place and functioning.
2. Verify that the facility is in compliance with internal benchmarks and
government regulations.
3. Assess past and current practices to identify and correct safety impediments
which may result in personal injuries, property damage or business interruption.
Safety audit is essential to determine the company’s safety and is a proactive
process by which and organization is able to continually evaluate and monitor
the progress of its safety and health programs. Safety audit involves the
examination and qualitative assessment of all activities such as research and
development, design, occupational health and hygiene, environmental control,
products and processes, storage and transportation, labeling and packing,
operational measures, maintenance, housekeeping and training. Auditing will
promote contact with individual workers as a manifestation of the management
interest and concern relating to safety. It is also essential that an appropriate
member of the management is directly involved in auditing and implementation
of the audit report. Audits are designed to rate an organization’s total safety and
health program, identify it’s strength and weakness , show where improvement
are needed , and obtain commitment and target dates for correcting problems.
1 mark
each
4
2-e Bin Storage:
Valuable materials are stored in bins, hoppers or siloswhich are cylindrical or
rectangular vessels made up of concrete or metal. Silo is relatively tall and
small in diameter, bin is fairly wide and short, hopper is a small bin with
4 4
MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION (Autonomous)
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SUMMER-16 EXAMINATION Model Answer
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sloping bottom which is used to temporarily store the solid before feeding the
solid to a process. Storage bins or hoppers are generally classified based upon
the flow pattern of bulk material discharged- core flow, mass flow and
composite flow. The actual pattern of flow within the container depends upon
the nature of bulk solid concerned as well as on the shape of the hopper.
Mass flow bins
Working: These are characterized by shallow angle of converging section. In
mass flow bin, every particle of the bulk material in the hopper begins to move
when the outlet is opened. Hence mass flow bins has steep wall slopes of the
converging sections. It has relatively large outlet to the feeder or flow control
valve. The cohesive solids stored in mass flow bins form cohesive arch at the
opening which acts as the obstruction to the gravity flow of material. It is
overcome by providing some discharge aid.
Core flow bins
Construction: In core flow bins the discharge of the bulk solid is essentially
irregular with the material flowing through a vertical channel called rat hole,
MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION (Autonomous)
(ISO/IEC - 27001 - 2005 Certified)
SUMMER-16 EXAMINATION Model Answer
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which forms within the bin. The material around this central channel is
stationary. The main characteristics of core flow bin are
1. First – in- last-out
2. The material gets spoil or degraded by caking in the non flow region.
3. The material which segregate on charging, there is no remixing in the
hopper.
4.Non uniform flow is obtained.
3 Any 4 16
3-a Causes of explosion hazard:
1. External source of energy
2. Internal exothermic reaction in which large volume of gases are
produced.
1 mark
each for
any 4
4
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3. The result of the release of internal energy during an uncontrolled
reaction.
4. High pressure inside the vessel due to heating
5. Dust explosion
3-b The objectives of material handling are:
i) Safety in material handling.
ii) Better housekeeping
iii) Minimization of fatigue.
iv) Speed and economy in movement of materials.
v) Minimization of cost of material handling.
vi) Improvement in productivity.
vii) Greater utilization of material handling equipment.
viii)higher plant efficiency
1 mark
each for
any 4
4
3-c Types of plant maintenance:
1. Preventive maintenance
2. Scheduled maintenance
3. Predictive maintenance
4. Breakdown maintenance
1 mark
each
4
3-d Objectives of Preventive Maintenance are :
i) To minimize the possibility of unanticipated production interruption or major
breakdown by locating or uncovering any condition this may lead to it.
ii) To make plant equipment and machinery always available and ready for use.
iii) To maintain the value of equipment and machinery by periodic inspection
repairs etc.
iv) To maintain the optimum productive efficiency of the plant equipment and
machinery.
v) To maintain the operational accuracy of the plant equipment.
1 mark
each for
any 4
4
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SUMMER-16 EXAMINATION Model Answer
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vi) To reduce the work content of the maintenance jobs.
vii) To achieve maximum production at minimum repair cost.
viii) To ensure safety of life and limbs of the workmen.
3-e ON LINE MAINTENANCE; In a chemical plant it is normal practice to do
on linemaintenance work. This avoids total shutdown of the equipment or plant.
This is possible if proper pipe fittings are installed at the time of erection .e.g.
suppose there is a rotameter in a pipe line. If we desired to replace a
brokenglass pipe of rotameter we can closed valve 1 and 2 and open 3 & divert
thefluid through by-pass line. After replacement of the glass pipe in the
rotameter close valve 3 and open 1 & 2. Thus it is possible to attend
maintenance jobs in the line without stopping the production.
4 4
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4-A Any 3 12
4A-a Fire: Fire is defined as the self-propagating reaction of a material with oxygen
in airwhich results in rapid energy release usually in the form of light or heat.
Three types of fire in process industries are
Fire may be extinguished by withdrawal of flammable contents,
interruptingflammable flow, isolating fuel from air, heat removal to below
reactiontemperature.
Withdrawal of flammable contents can be accomplished by 1).Blowing
down the vessel and piping contents ( 2)Pump out or 3)drainingFlammable
flow may be interrupted by the shutdown of pumps, closing ofvalves.
Isolation of flammable flow from the air is accomplished by blanketing
withsteam or water spray, foam, CO2 etc.
1
3
4
4A-b The causes of equipment breakdown are: 1 mark 4
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a) Failure to replace worn out parts.
b) Lack of lubrication.
c) Neglecting cooling system.
d) Indifference towards minor faults.
e) External forces e.g. too low or too high voltage, wrong fuel etc.
f) Indifference towards equipment vibrations, unusual sounds coming out of
rotating machinery, excessive heating of equipment etc.
each for
any 4
4A-c Palletization is the method of storing and transporting goods stacked on a
pallet and shipped as a unit load. It permits standardized ways of handling loads
with common mechanical equipment such as fork lift trucks.
Based on design pallets are classified as:
i) Two way pallets
ii) Four way pallets
Based on basic construction style pallets are classified as
i) Single face pallet
ii)double face pallet
Based on construction pallets are classified as
i) Flush stringer
ii) Single wing
iii) Double wing
1
1
1
1
4
4A-d
Methods of liquid storage:
Underground storage:
*Liquids are stored underground in porous media between impervious rocks.
Cavities are formed in salt domes by dissolving the salt and pumping it out.
This method has application for storing petroleum product, both liquid and
gasses. Hazardous or radioactive materials are stored in underground tunnels or
storage tanks
4 4
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Open atmospheric tanks:
*Open atmospheric tanks are used for storing liquids that will notbe harmed by
water, weather or atmospheric pollution.
The closed tanks:
*The closed tanks have fixed or floating roof. Fixed roofs are either domed
orconed with intermediate supports.
*Fixed roof atmospheric tanks require vents to prevent pressure changes
whichwould result from temperature changes and withdrawal or addition of
liquid.
*Vent loss is prevented by using variable volume tanks which have floating
roofs.Floating roof must have a seal between roof and tank shell.
*For storing liquids under pressure, the tank has curved surface in the form
ofsphere ellipsoid shapes.
*Plastics or glass coating are applied to the corrosive liquids which are to be
stored in glass lined tanks.
4-B Any one 6
4B-a Procedure for safety auditing:
Safety audit is carried out by a team whose members are not involved in the
plant or activity being audited. The expertise of the team should be compatible
with the type of audit. It is beneficial to include the managers of other plants or
units in an audit team as well as one previous auditor of the same unit. Audits
are carried out in a formal way using a carefully drawn up checklist of items
and descriptive standards for each item. A line manager or supervisor of the
plant under audit should be asked to accompany the auditor inspecting it. He
should be informed of all corrections and improvements required by the
auditors so that he can start taking the necessary steps before the audit report is
submitted to management. The main object of inspection should be to
6
6
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determine whether the layout design and condition of equipment and protective
features are up to standard and to ensure that the protective features will work
in an emergency. The auditing should give a verbal report to the management
on completion of audit followed by a clear and concise written report within
two weeks.
The main aspects of safety audit are:
i)Identification of possible hazardous situation
ii) Assessment of consequences associated with these hazards
iii) Selection of measures to minimize consequences.
iv) Implementation of these measures within the organization
v) Monitoring and documentation of the changes.
The methodology generally accepted and adopted for safety audit is the
preparation and submission of a questionnaire or checklist to the plant
management
4B-b Belt conveyor:
Working: Conveyors are gravity or power devices commonly used to move uniform loads
continuously from point to point over fixed paths. Belt conveyor as shown in
figure consists of an endless moving belt of flexible material, stretched between
two drums / pulleys and supported at intervals on idler rollers. The pulley that
drives conveyor belt rotating is called drive pulley or transmission drum; the
other one only used to change conveyor belt movement directions called bend
pulley. Drive pulley is driven by the motor through reducer and conveyor belt
2
4
6
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dragging relies on the friction drag between the drive pulley and the conveyor
belt. The drive pulleys are generally installed at the discharge end in order to
increase traction and be easy to drag. Material is fed on the feed-side and
landed on the rotating conveyor belt, then rely on the conveyor belt friction to
be delivered to discharge end.
Belt Conveyors are the most commonly used type of equipment for the
continuous transport of solids. They can carry wide range of materials
economically over long & short distances, both horizontally and at an
appreciable angle.
5 Any 2 16
5-a Construction & Working of Soda Acid Fire Extinguisher :
Construction: In soda acid fire extinguisher the material used are dry chemical,
bicarbonate of soda designed to be dissolved in water and a liquid chemical
sulphuric acid. Sulfuric acid is kept in the acid bottle and sodium bicarbonate
in the outer body. Nozzle is provided near the top and aplunger at the top.
Working:
When the plunger is struck, it breaks the acid bottle. The sulfuric acid and the
sodium bicarbonate solution react together to release CO2 gas. The gas
generated creates pressure, which forces the water out of the extinguisher
nozzle. Before using these extinguisher, it is advisable to check whether these
extinguishers are upright type or turn over type. Direct the jet at the base of
the fire and sweep it across the area of fire. Attack a vertically spreading fire at
its lowest point and follow it up. Search out for hot spots and ensure that the
fire is completely extinguished and that it is not smouldering.
2
3
8
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3
5-b Functions and responsibilities of plant maintenance department:
1)Inspection 2)Engineering 3) Maintenance 4) Repair 5) Overhaul
6)Construction 7) Salvage 8) Clerical work
1)Inspection:
i) Inspection of the plant facilities to examine their condition and to check for
repairs needed.
ii) Inspection to ensure the safe and efficient operation of plant equipment and
machinery.
2)Engineering :
i) Engineering involves alternations and improvement in existing plant
equipment to minimize breakdown.
ii) Engineering and consulting services to production supervision.
3) Maintenance :
i) Maintenance of existing plant equipment.
ii) Engineering and execution of planned maintenance, minor installations of
equipment building and replacements.
1 mark
each
8
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4) Repair:
i) To carry out corrective repair to alleviate unsatisfactory conditions found
during preventive maintenance inspection.
5) Overhaul:
i) Overhaul is a planned, scheduled reconditioning of plant facilities such as
machinery etc.
ii) Overhaul involves replacement, reconditioning, reassembly, etc.
6)Construction :
i) In some organization, maintenance department is provided with equipment
and personnel and it takes up construction job too.
7) Salvage :
i) Maintenance department may also handle disposition of scrap or surplus
materials.
8) Clerical work:
i) Maintenance department keeps records at i) of costs, ii) of time progress on
jobs pertaining to important features of building and production equipment.
5-c Start up of a plant:
A chemical plant is started at two different times,
1. When it is constructed, erected and to be commissioned first time for
production. The procedure here to be followed is to take water in the
plant to check the fluid flowing through equipment and pipelines
without any leakage, at the desired flow rate, pressure and temperature.
If any leakage is observed, it can be rectified. This is the safest and
cheapest way of checking the functioning of the plant equipment in
total.
2. When plant is stopped for annual major shutdown, then the procedure
to be followed for start- up of a plant is
4
8
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i) To take water in the plant to check the fluid flowing through equipment
and pipelines without any leakage, at the desired flow rate, pressure and
temperature. If any leakage is observed, it can be rectified. Thus is the
safest and cheapest way of checking the functioning of the plant
equipment in total.
ii) Once it is assured that fluid flow takes place without any problem, the
total plant water is drained off and water is removed and then slowly
loaded in stepwise and retched to desire capacity in stepwise. It is
always advisable to operate the plant with 50% capacity for few days
and after full satisfaction of plant working, it is taken up to full capacity
4
6 Any 2 16
6-a Pneumatic conveyor:
Different types are:
1. Positive pressure pneumatic conveyor
2. Negative pressure pneumatic conveyor
3. Pressure-vacuum system
4. Fluidising system
5. Blow tank
Positive Pressure or Vacuum Systems:
Air or suitable gas is blown along a pipeline, which carries the bulk solid to be
conveyed. Fan or blower is used to deliver air into the pipeline. Feeders are
used to introduce the material into the pipeline against the conveying gas
pressure. Gas/ solid disengaging device is used at the discharge end of the
pipeline, which separates the conveyed bulk solid from the conveying air
stream. The cyclone separator or bag filter units are used for this purpose. The
clean gas/ air coming out from these devices is fed back for conveying purpose.
These systems are useful for picking up solid from one point band delivering
3
5
4
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them to various discharge points. They are used for free flowing materials upto
¼ inch size. But it is unsuitable for multiple pick up points on account of excess
air leakage.
6-b Block diagram of organization of maintenance department 8 8
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6-c Predictive maintenance:
Predictive maintenance makes use of human sense or other sensitive
instruments such as audio gauges, vibration analyser, amplitude meter ,
pressure , temperature and resistance strain gauges etc. to predict trouble before
the equipment fails. Unusual sounds coming out of a rotating equipment
predict a trouble , an electric cable excessively hot at one point predict a
trouble. Simple hand touch can point out many unusual conditions and thus
predict a trouble. In predictive maintenance , equipment conditions are measure
periodically or on a continuous basis and this enables maintenance men to take
a timely action such as equipment adjustment , repair or overhaul. Predictive
maintenance extends the service life of an equipment without fear of failure.
Four senses adopted for predictive maintenance technique (Human senses) :
4
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1. Ear :eg. Unusual sound coming out of rotating equipment.
2. Eye :eg. Excessive vibration of equipment or dislocation of moving
part.
3. Touch :eg. Excessive temperature of equipment.
4. Smell :eg. Unusual smoke coming out of equipment.
Four sensitive instruments adopted for predictive maintenance technique:
1. Audio gauges :eg. Unusual sound coming out of rotating equipment.
2. Vibration analysor: eg. Excessive vibration of equipment
3. Amplitude meter:eg. Excessive temperature of equipment.
4. Pressure, temperature and resistance strain gauges: eg. Excessive
temperature of equipment.
Scheduled maintenance:
Scheduled maintenance is a stich-in-time procedure which is aimed at avoiding
breakdowns. Breakdowns can be dangerous to life and hence should be
minimized.
This method of maintenance incorporates inspection, lubrication, repair and
overhaul of certain equipments which if neglected may result in breakdown.
Scheduled maintenance practice is generally adopted for overhauling of
machines, cleaning of water and other tanks, white washing of buildings
etc.
4